WO2004102548A1 - Optical pick-up unit - Google Patents

Optical pick-up unit Download PDF

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Publication number
WO2004102548A1
WO2004102548A1 PCT/IB2004/001499 IB2004001499W WO2004102548A1 WO 2004102548 A1 WO2004102548 A1 WO 2004102548A1 IB 2004001499 W IB2004001499 W IB 2004001499W WO 2004102548 A1 WO2004102548 A1 WO 2004102548A1
Authority
WO
WIPO (PCT)
Prior art keywords
lens
unit
optical pick
counterweight
arrangement
Prior art date
Application number
PCT/IB2004/001499
Other languages
French (fr)
Inventor
John A. Harold-Barry
Original Assignee
Koninklijke Philips Electronics N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2004102548A1 publication Critical patent/WO2004102548A1/en

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0946—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following specially adapted for operation during external perturbations not related to the carrier or servo beam, e.g. vibration
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0925—Electromechanical actuators for lens positioning
    • G11B7/0933—Details of stationary parts
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0925—Electromechanical actuators for lens positioning
    • G11B7/0935—Details of the moving parts

Definitions

  • the present invention relates to an optical pick-up unit particularly for use within an optical disk drive of, for example, a portable device.
  • a lens supporting structure including a resilient lens supporting means which allows for the driven movement of the lens, primarily by way of an electrical servo system, such that the lens can be moved in a so-called focusing direction towards, and away from, the surface of a rotating optical disk.
  • the resilient supporting means for the lens can be preloaded upwardly so as to compensate for the force of gravity on the lens. Such preloading then limits the manner in which the electrical servo system has to continuously dissipate power when supporting the lens against the force of gravity.
  • the present invention seeks to provide for an optical pick-up unit having advantages over known such units and, in particular, which can reduce the power dissipation otherwise arising due to static acceleration in a variety of orientations.
  • an optical pick-up unit having a lens resiliently mounted and arranged to be driven for movement in a focusing direction; at least one connection member connecting the lens to a support at a pivot point and about which the lens pivots when driven in the focusing direction; wherein the at least one connection member is also connected to a counterweight arrangement located on an opposite side of the pivot point from the lens so as to provide for a counterweight to the said lens, the counterweight arrangement also being resiliently mounted within the unit.
  • the counterweight can be arranged to become effectively decoupled from the lens within the control loop bandwidth of the unit. Then, at relatively low frequencies, the counterweight and lens appear coupled, but at high frequencies the lens becomes substantially independent of the counterweight arrangement.
  • Claims 2, 3 and 4 prove particularly advantageous in providing for a simplified mechanical arrangement for achieving the required damping and which, as confirmed by the subject matter of Claim 11 , can provide for damping in relation to the radial movement of the lens with respect to an optical disk.
  • the use of the counterweight arrangement in relation to the pivot points allows for a readily variable, and selectable, means for resiliently mounting the counterweight and lens so as to vary the damping of the lens and counterweight arrangement.
  • Fig. 1 is a schematic plan view of an optical pick-up unit embodying the present invention
  • Fig. 2 is a schematic cross selection taken along lines II -II of Fig. 1.
  • FIG. 1 there is provided, as a schematic diagram, a plan view of one arrangement for an optical pick-up unit 10 embodying the present invention.
  • the optical pick-up unit 10 includes a lens 12 which is arranged to be driven both in focusing direction and a radial direction having regard to an optical disk (not shown) by means of an electrical servo system (not shown).
  • the lens 12 is mounted within a lens holder 14 which, in turn, is mounted to lateral lens supports 16.
  • Each one of the lateral lens supports 16 is mounted to the end of a respective connecting member 18,20 by which the lens arrangement 12, 14 is effectively pivotally connected to respective support posts 22, 24 extending from the chassis 34 (see Fig. 2) of the optical pick-up unit 10.
  • connection to the support posts 22,24 is achieved by way of respective glue hinges 26,28.
  • each of the connecting members 18,20 include respective portions 18'20' extending beyond the respective glue hinges 26,28 for connection to laterally extending supports 30 of a counterweight arrangement including a counterweight mass 32.
  • the counterweight mass 32, and the respective lengths of the connecting member sections 18, 18' and 20, 20' are such that the mass of lens arrangement 12, 14 is equal to the mass of the counterweight mass 32 and the sections 18,20 of the connecting members are equal in length to the extended sections 18', 20'.
  • FIG. 2 there is provided a cross-sectional view along the line ll-ll of Fig. 1 and which clearly shows the counterbalancing effect achieved by the lens arrangement 12, 14 and the counterweight mass 32 either side of the glue hinge 28 providing a pivot point of connection for the connecting member 20, 20' to the chassis 34.
  • a particular advantage of the present invention arises from the manner in which the counterbalancing movement of the lens 12 can be achieved.
  • the counterweight mass 32 provides for counterbalancing when the lens 12 is driven for movement in a radial direction along the direction of arrow A and parallel to the plain off an optical disk (not shown).
  • the counterweight mass 32 also provides for counterbalancing as the lens 12 is moved in the direction of arrow B, i.e. as the lens 12 is driven for movement towards, or away from, the surface of the optical disk in the focusing direction.
  • the counterbalancing, and related damping can be provided in the at least two aforementioned perpendicular plains.
  • connection members 18, 18' and 20,20' in the form of springs, the double mass otherwise presented by inclusion of the counterbalance mass 32 along with the weight of the lens arrangement 12, 14 is then effectively seen at low frequencies only and so does not increase power dissipation if the effective decoupling occurs below the minimum rotational frequency.
  • the counterweight mass in the manner illustrated as a counterbalance to the mass of the lens arrangement, the static dissipation can be removed for any angle and orientation with respect to gravity and low frequency acceleration.
  • the present invention is therefore particularly advantageous for use in optical drives of, for example portable devices such as in mobile phones.
  • the preset invention advantageously remains effective during the high acceleration arising during initial access of the data stored on the disk.
  • the mounting of the lens arrangement 12, 14 and the counterbalancing mass 32 by means of the resilient connecting members 18,18' and 20,20' which may take the form of leaf springs, provides for a coupling between the lens arrangement 12, 14 and counterbalance mass 32 at low frequencies whereas, at high frequencies, for example greater than 100 HZ, the lever springs 18,18' and 20,20' effectively decouple the lens arrangement 12, 14 from the counterbalance mass 32 such that the one appears independent of the other.
  • any appropriate counterbalancing configuration can be provided and the relative stiffness of the respective resilient mounting means for the lens arrangement and the counterbalancing mass can be selectively different, so as to control the respective damping and thereby control the lens resonance.

Landscapes

  • Optical Recording Or Reproduction (AREA)

Abstract

The present invention provides for an optical pick-up unit for use within an optical disk drive and having a lens resiliently mounted and arranged to be driven for movement in a focusing direction, at least one connection member connecting the lens to a support at a pivot point and about which the lens pivots when driven in the focusing direction, wherein the at least one connection member is also connected to a counterweight arrangement located on an opposite side of the pivot point from the lens so as to provide for a counterweight to the said lens, the counterweight arrangement also being resiliently mounted within the unit.

Description

DESCRIPTION
OPTICAL PICK-UP UNIT
The present invention relates to an optical pick-up unit particularly for use within an optical disk drive of, for example, a portable device.
In currently known optical pick-up units there is provided a lens supporting structure including a resilient lens supporting means which allows for the driven movement of the lens, primarily by way of an electrical servo system, such that the lens can be moved in a so-called focusing direction towards, and away from, the surface of a rotating optical disk. In order to prevent the electrical servo system having to continuously dissipate power in lifting the lens against the force of gravity, the resilient supporting means for the lens can be preloaded upwardly so as to compensate for the force of gravity on the lens. Such preloading then limits the manner in which the electrical servo system has to continuously dissipate power when supporting the lens against the force of gravity.
Disadvantages are however inherent in such known arrangements and particularly when provided in optical drives in which the orientation of the drive can not be predetermined and is required to be varied such as, for example, in small form factor and other portable optical drives. In such devices, it will be appreciated that the lens supporting arrangement may be required to operate in any orientation such as those described above were used, for example in an upside down orientation. As will then be appreciated, should the drive be used in an inverted orientation, twice the power will have to be dissipated by the electrical servo system since it would then not only have to work against the force of gravity, but also against the preloading of the resilient supporting arrangement.
The present invention seeks to provide for an optical pick-up unit having advantages over known such units and, in particular, which can reduce the power dissipation otherwise arising due to static acceleration in a variety of orientations.
According to the present invention, there is provided an optical pick-up unit having a lens resiliently mounted and arranged to be driven for movement in a focusing direction; at least one connection member connecting the lens to a support at a pivot point and about which the lens pivots when driven in the focusing direction; wherein the at least one connection member is also connected to a counterweight arrangement located on an opposite side of the pivot point from the lens so as to provide for a counterweight to the said lens, the counterweight arrangement also being resiliently mounted within the unit.
Advantageously, by incorporating such a compensating weight as a counter balance for the mass of the lens, it is found that the static power dissipation can be removed for any particular angle of orientation with respect to gravity or indeed having regard in general to low frequency acceleration movements.
The provision of the resilient mounting of both the lens and the counterweight arrangement advantageously allows for damping within the mounting arrangement for the lens and which can advantageously exhibit different high and low frequency oscillation properties.
Further, in providing for the resilient mounting of both of the lens and the counterweight arrangement, the counterweight can be arranged to become effectively decoupled from the lens within the control loop bandwidth of the unit. Then, at relatively low frequencies, the counterweight and lens appear coupled, but at high frequencies the lens becomes substantially independent of the counterweight arrangement.
A reduction in the power dissipation experienced within the prior-art is therefore achieved in a particularly advantageous manner.
The features of Claims 2, 3 and 4 prove particularly advantageous in providing for a simplified mechanical arrangement for achieving the required damping and which, as confirmed by the subject matter of Claim 11 , can provide for damping in relation to the radial movement of the lens with respect to an optical disk.
Such advantages are further emphasised by the features of Claims 6, 7 and 8 concerning the manner of mounting the counterweight arrangement.
Also, as appreciated by the subject matter of Claims 9 and 10, the use of the counterweight arrangement in relation to the pivot points allows for a readily variable, and selectable, means for resiliently mounting the counterweight and lens so as to vary the damping of the lens and counterweight arrangement.
The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings in which:
Fig. 1 is a schematic plan view of an optical pick-up unit embodying the present invention; and Fig. 2 is a schematic cross selection taken along lines II -II of Fig. 1.
Turning now to Fig. 1 , there is provided, as a schematic diagram, a plan view of one arrangement for an optical pick-up unit 10 embodying the present invention. The optical pick-up unit 10 includes a lens 12 which is arranged to be driven both in focusing direction and a radial direction having regard to an optical disk (not shown) by means of an electrical servo system (not shown).
The lens 12 is mounted within a lens holder 14 which, in turn, is mounted to lateral lens supports 16. Each one of the lateral lens supports 16 is mounted to the end of a respective connecting member 18,20 by which the lens arrangement 12, 14 is effectively pivotally connected to respective support posts 22, 24 extending from the chassis 34 (see Fig. 2) of the optical pick-up unit 10.
In the illustrated embodiment, the connection to the support posts 22,24 is achieved by way of respective glue hinges 26,28.
According to a particular feature of the illustrated embodiment, each of the connecting members 18,20 include respective portions 18'20' extending beyond the respective glue hinges 26,28 for connection to laterally extending supports 30 of a counterweight arrangement including a counterweight mass 32.
In this illustrated example, the counterweight mass 32, and the respective lengths of the connecting member sections 18, 18' and 20, 20' are such that the mass of lens arrangement 12, 14 is equal to the mass of the counterweight mass 32 and the sections 18,20 of the connecting members are equal in length to the extended sections 18', 20'.
Turning now to Fig. 2, there is provided a cross-sectional view along the line ll-ll of Fig. 1 and which clearly shows the counterbalancing effect achieved by the lens arrangement 12, 14 and the counterweight mass 32 either side of the glue hinge 28 providing a pivot point of connection for the connecting member 20, 20' to the chassis 34.
A particular advantage of the present invention arises from the manner in which the counterbalancing movement of the lens 12 can be achieved.
With reference to arrow A in Fig. 1 it will be appreciated that the counterweight mass 32 provides for counterbalancing when the lens 12 is driven for movement in a radial direction along the direction of arrow A and parallel to the plain off an optical disk (not shown). In Fig. 2, it will be appreciated that the counterweight mass 32 also provides for counterbalancing as the lens 12 is moved in the direction of arrow B, i.e. as the lens 12 is driven for movement towards, or away from, the surface of the optical disk in the focusing direction.
Thus, as illustrated in this embodiment, the counterbalancing, and related damping, can be provided in the at least two aforementioned perpendicular plains.
By providing the connection members 18, 18' and 20,20' in the form of springs, the double mass otherwise presented by inclusion of the counterbalance mass 32 along with the weight of the lens arrangement 12, 14 is then effectively seen at low frequencies only and so does not increase power dissipation if the effective decoupling occurs below the minimum rotational frequency. As will be appreciated, by including the counterweight mass in the manner illustrated as a counterbalance to the mass of the lens arrangement, the static dissipation can be removed for any angle and orientation with respect to gravity and low frequency acceleration. The present invention is therefore particularly advantageous for use in optical drives of, for example portable devices such as in mobile phones.
The preset invention advantageously remains effective during the high acceleration arising during initial access of the data stored on the disk.
As mentioned previously, the mounting of the lens arrangement 12, 14 and the counterbalancing mass 32 by means of the resilient connecting members 18,18' and 20,20', which may take the form of leaf springs, provides for a coupling between the lens arrangement 12, 14 and counterbalance mass 32 at low frequencies whereas, at high frequencies, for example greater than 100 HZ, the lever springs 18,18' and 20,20' effectively decouple the lens arrangement 12, 14 from the counterbalance mass 32 such that the one appears independent of the other.
While it is appreciated that such decoupling frequency will have a resonance associated with it and which will need to be damped to some extent, it is considered that damping will generally be applied closer to the counterbalance mass 32 since it is generally the lens that is arranged to be driven by the electrical servo system.
It should be appreciated that the invention is not restricted to the details of the foregoing illustrated embodiment. For example, any appropriate counterbalancing configuration can be provided and the relative stiffness of the respective resilient mounting means for the lens arrangement and the counterbalancing mass can be selectively different, so as to control the respective damping and thereby control the lens resonance.

Claims

1. An optical pick-up unit having a lens resiliently mounted and arranged to be driven for movement in a focusing direction; at least one connection member connecting the lens to a support at a pivot point and about which the lens pivots when driven in the focusing direction; wherein the at least one connection member is also connected to a counterweight arrangement located on an opposite side of the pivot point from the lens so as to provide for a counterweight to the said lens, the counterweight arrangement also being resiliently mounted within the unit.
2. An optical pick-up unit as claimed in Claim 1 , wherein the at least one connection member provides for the resilient mounting of the lens.
3. An optical pick-up unit as claimed in Claim 2, wherein the at least one connection member comprises a leaf spring.
4. An optical pick-on unit as claimed in Claim 1 , 2, or 3, wherein the connecting member is connected to the pivot point by means of a glue hinge.
5. An optical pick-up unit as claimed in any one or more of Claims 1-4, wherein the resilient mounting of the lens is preloaded.
6. An optical pick-up unit as defined in any one or more of Claims 1- 5, wherein the connection of the at least one connection member to the counterweight arrangement provides for the resilient mounting of the counterweight arrangement.
7. An optical pick-up as claimed in Claim 6, wherein the connection member connecting to the counterweight arrangement comprises a leaf spring.
8. An optical pick-up unit as claimed in any one ore more of Claims 1-7, wherein the at least one connection member extends to connect to both the lens and the counterweight arrangement.
9. An optical pick-up unit as claimed in any one or more of Claims
1-8, wherein the mass of the counterweight is equal to the mass of the lens.
10. An optical pick-up unit as claimed in any one or more of Claims 1-9, wherein the distance of the lens to the pivot point is the same as the distance of the counterweight arrangement to the pivot point.
11. An optical pick-up unit as claimed in any one or more of Claims 1-10, wherein the connection of the counterweight arrangement is arranged to provide for a counterweight effective for pivotal motion about the pivot point in a focusing direction and also in a radial direction.
12. An optical disk drive including an optical pick-up unit as claimed in any one or more of Claims 1-11.
PCT/IB2004/001499 2003-05-13 2004-05-05 Optical pick-up unit WO2004102548A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0310926.1 2003-05-13
GB0310926A GB0310926D0 (en) 2003-05-13 2003-05-13 Optical pick-up unit

Publications (1)

Publication Number Publication Date
WO2004102548A1 true WO2004102548A1 (en) 2004-11-25

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ID=9957940

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2004/001499 WO2004102548A1 (en) 2003-05-13 2004-05-05 Optical pick-up unit

Country Status (2)

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GB (1) GB0310926D0 (en)
WO (1) WO2004102548A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1475791A2 (en) * 2003-05-01 2004-11-10 Systems Engineering Co. Ltd Optical pickup lens driving apparatus

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5461598A (en) * 1992-09-18 1995-10-24 Eastman Kodak Company Balanced focus actuator for an optical storage system
EP0935241A1 (en) * 1997-08-27 1999-08-11 Nhk Spring Co.Ltd. Objective actuator
US20020141323A1 (en) * 2001-02-05 2002-10-03 Masami Horita Optical pickup device
US20030072244A1 (en) * 2001-10-12 2003-04-17 Funai Electric Co., Ltd. Objective lens supporting apparatus and optical pickup

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5461598A (en) * 1992-09-18 1995-10-24 Eastman Kodak Company Balanced focus actuator for an optical storage system
EP0935241A1 (en) * 1997-08-27 1999-08-11 Nhk Spring Co.Ltd. Objective actuator
US20020141323A1 (en) * 2001-02-05 2002-10-03 Masami Horita Optical pickup device
US20030072244A1 (en) * 2001-10-12 2003-04-17 Funai Electric Co., Ltd. Objective lens supporting apparatus and optical pickup

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1475791A2 (en) * 2003-05-01 2004-11-10 Systems Engineering Co. Ltd Optical pickup lens driving apparatus
EP1475791A3 (en) * 2003-05-01 2006-03-01 System Engineers' Co. Ltd. Optical pickup lens driving apparatus

Also Published As

Publication number Publication date
GB0310926D0 (en) 2003-06-18

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